The disclosure relates to a pneumatic valve arrangement for a pneumatically operated field device, in particular a control device, of a processing plant, such as a chemical plant, a foodstuff processing plant, a power plant or the like.
Pneumatic valve arrangements comprise an air supply conduit for receiving pressurized air from a source of pressurized air, a control air conduit for aerating and venting a pneumatic actor such as a pneumatic actuating drive (e.g., a pneumatic linear actuating drive with spring return or a dual action pneumatic actuating drive of the field device), and a venting conduit for discharging pressurized air to a pressure sink, such as the atmosphere. In known pneumatic valve arrangements, the fluidic connection between the three air channels, that is to say the air supply conduit, the control air conduit, and the venting conduit, is controlled by at least one air control valve, so that pressurized air can be supplied from the source of pressurized air to the pneumatic actor of the field device, or discharged to the pressure sink in controlled manner.
A pneumatic valve arrangement which has enjoyed great popularity for years is known, for example, from German patent application no. DE 195 05 233 A1. This known pneumatic valve arrangement comprises a housing and a fluid chamber that is conformed inside the housing, into which one fluid inlet conduit opens and from which two fluid outlet conduits depart. One of these leads to a pressure sink and the other to a pneumatic actor of a pneumatic field device. An electromagnet is provided in the pneumatic valve arrangement and actuates a spring-biased hinged armature to move the hinged armature between a position in which the conduit opening of the fluid inlet conduit is closed, and a position in which the conduit opening of the fluid outlet conduit leading to the pressure sink is closed.
A further popular pneumatic valve arrangement is known, for example, from German patent application no. DE 10 2007 062 207 A1. This pneumatic valve arrangement may be embodied as a pneumatic booster for displacing an actuating fitting of a processing plant. The pneumatic valve arrangement comprises a connecting line for sending an amplified pneumatic output signal to an actuating fitting or a pneumatic actor. The connecting line is provided between an air infeed valve and an air discharge valve. A pilot signal for a pneumatic actuating drive, which has been amplified by a pneumatic supply system, may be specified for the connecting line through the air infeed valve. The connecting line may be set to atmospheric pressure through the air discharge valve. The air infeed and air discharge valves are each equipped with a pneumatically controlled tappet, which are actuated with a pneumatic pilot signal. In order to produce the pneumatic pilot signal, pressurized air is tapped from the pneumatic supply system upstream of the air infeed valve via a throttle, and the pneumatic pilot signal is set for the air infeed valve and the air discharge valve by adjusting a discharge air control baffle plate.
More and more users are expressing the desire for both electrically and pneumatically highly energy-efficient pneumatic valve arrangements.
The exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In the drawings, the same or similar reference signs are used for identical or similar components.